The role of insulin resistance and consecutive hyperinsulinemia in the pathogenesis of non-insulin dependent diabetes (NIDDM) and atherosclerosis is firmly established, Olefsky, J. M., et al, "Insulin Action and Resistance in obesity and non-insulin dependent type II diabetes mellitus," Am. J. Physiol. 1982; 243:E15-E30. Reaven, G. M., "Role of insulin resistance in human disease," Diabetes 1988; 37:1595-1607. Stout, R. W., "Insulin and atheroma--an update," Lancet 1987; I;1077-1079. Recently the atherogenic risk of elevated insulin concentrations in prediabetic insulin resistant states like obesity, glucose intolerance, essential hypertension and --surprisingly--in "healthy" subjects with normal oral glucose tolerance has gained increasing interest, Ferrannini, E., et al, "Insulin resistance in essential hypertension," N. Engl. J. Med. 1987; 317:350-357. Standl, E., "Hyperinsulinamie -eine Ursache der Makroangiopathie?" Akt Endokr Stoffw 1989; 10:41-46 (Sonderheft). Stout, R. W., supra, Torlone E., et al, "Effects of captopril on insulin-mediated carbohydrate and lipid metabolism in subjects with NIDDM and hypertension, "Diabetes 1989; 38(Suppl. 2):88A. Hyperinsulinemia appears to be the earliest and strongest detectable risk factor for coronary heart disease, Eschwege, E., et al, "Coronary heart disease mortality in relation with diabetes, blood glucose and plasma insulin levels. The Paris Prospective Study, ten years later," Horm. Metab. Res. Suppl. 1985; 15:41-46. Modan, M., et al, "Hyperinsulinemia--a link between glucose intolerance, obesity, hypertension, dyslipoproteinaemia, elevated serum uric acid and internal kation imbalance," Diab. Met. 1987; 13:375-380, and as a recent prospective study showed, insulin resistant hypertensive subjects have a markedly elevated risk to develop NIDDM in addition to their already high atherogenic risk, Skarfors, E. T., et al, "Do antihypertensive drugs precipitate diabetes in predisposed man?" Br. Med. J. 1989; 298:1147-1152.
Pollare, T., et al, "Insulin Resistance is a Characteristic of Primary Hypertension Independent of Obesity," Metabolism, Vol. 38, No. 12 (Dec.), 1989:pp 1-9 discloses that hypertension is associated with hyperinsulinemia independently of either obesity or glucose tolerance.
Pollare T., al al, "A comparison of the Effects of Hydrochlorothiazide and Captopril on Glucose and Lipid metabolism in Patients with Hypertension," New England Journal of Medicine, 321:888-873 (Sept. 28) 1989, disclose that captopril appears to have beneficial or no effects on glucose and lipid metabolism.
In a recent randomized multicenter study performed with general practitioners in West Germany, it was found that out of 243 treated essential hypertensive patients, only 35.9% had a normal oral glucose tolerance test, while 40.6% had impaired glucose tolerance (IGT) and 23.5% manifest NIDDM. The vast majority of patients observed was hyperinsulinemic, Rett, K., et al, "Metabolic effects of Metoprolol versus Captopril in essential hypertension," Dtsch. Med. Wschr. (in preparation). This suggests, that among hypertensive subjects, there might be an even higher number of patients with glucose intolerance as previously expected. These subjects are at risk of developing both coronary artery disease and diabetes.
There is evidence that ACE-inhibition (ACEI) is able to positively influence insulin resistance, Rett, K., et al, "Verbesserte Insulinwirkung durch ACE-Hemmung beim Type 2-Diabetiker," Dtsch. Med. Wschr. 1988; 243-249. Rett, K., et al, "Role of angiotensin-converting enzyme inhibitors in early anti-hypertensive treatment in non-insulin dependent diabetes mellitus," Postgrad Med. J. 1989a; 64(Suppl. 3):69-73. Torlone, E., et al, supra, Rett, K., et al, "Angiotensin converting enzyme inhibitors in diabetes: Experimental and human experience," Postgrad. Med. J. (U.K.), 1986 62/Suppl. 1 (59-64)), and glucose metabolism in NIDDM. (Jauch, K., et al, "Captopril enhances insulin responsiveness of forearm muscle tissue in non-insulin-dependent diabetes mellitus," Eur. J. Clin. Invest. (U.K.), 1987, 17/5 (448-454)).
Edelman, S. et al, N. Engl. J. Med. (320, No. 18, 1219-20, 1989), "Hyperkalemia During Treatment with HMG CoA Reductase Inhibitor," discloses a case where a patient received lovastatin (ls) for hyperlipidemia and whose hypertension was initially well controlled with lisinopril. "LS treatment was started when cholestyramine and niacin treatment was not successful. The patient developed myositis and hyperkalemia and recovered after emergency treatment and withdrawal of LS. He later resumed taking LS (without consultation) and again developed severe myositis and hyperkalemia. He recovered when LS was withdrawn. Care is cautioned when LS and lisinopril are given in combination to patients at risk of hyperkalemia."
European Patent Application 0219782 to Scholkens (Hoechst) discloses the treatment of atherosclerosis, thrombosis and/or peripheral vascular disease in mammals using an angiotensin converting enzyme (ACE) inhibitor or its physiologically tolerable salts. It further discloses that because ACE is predominantly localized in the luminal plasma membrane of the endothelial cell, ACE inhibitors can interfere in platelet-endothelium interaction. In addition, Scholkens dislcoses that ACE inhibition potentiates the action of bradykinin (a strong stimulator of prostacyclin release from endothelial cells) by inhibiting its degradation and ACE inhibitors, consequently, have an inhibitory effect on platelet aggregation.
Zorn, J. et al, "Prevention of Arteriosclerotic Lesions with Calcium Antagonists or Captopril in Different Rat Hypertension Models," J. Cardiovasc. Pharmacol. Vol. 12 (Suppl 6), 1988, discloses beneficial effects in mesenteric arteries atherosclerosis with captopril in spontaneous hypertensive Okamoto rats (SHRs), but not in salt-sensitive Dahl rats.
Someya, N. et al, "Suppressive Effect of Captopril on Platelet Aggregation in Essential Hypertension," J. Cardiovasc. Pharmacol. 6:840-843, 1984, discloses at page 840 that "hypertension is closely related to the genesis and progress of atherosclerosis," and that "platelet function plays an important role in atherosclerosis, with platelet dysfunction demonstrable in several vascular diseases. It has been reported that platelet aggregation is increased in hypertensives . . . . " At page 842, it is indicated that the "data demonstrated the inhibition of platelet aggregation in vivo after administration of captopril to hypertensive subjects . . . . " At page 843, it is indicated that "platelet aggregability is greater in hypertensives than in normotensives . . . platelet abnormalities may be a risk factor in atherosclerosis . . . . If captopril possesses an antiplate aggregability effect in addition to its hypotensive effect, it may be very useful for the prevention of atherosclerosis and thrombotic diseases associated with hypertension."
Mizuno, K. et al "The effects of the angiotensin I-converting enzyme inhibitor, captopril, on serum lipoperoxides level and the renin-angiotensin-aldosterone and kallikrein-kinin systems in hypertensive patients," Nippon Naibunpi Gakkai Zasshi, Feb. 20, 1984, discloses that captopril is a beneficial antihypertensive agent for preventing serum lipoperoxides concentration (LPX)-induced atherosclerosis in hypertensive patients.
Mizuno, K. et al "Acute effects of captopril on serum lipid peroxides level in hypertensive patients," Tohoku J. Exp. Med., May, 1984, 143(1) p. 127-8, suggests that inhibition of angiotensin-converting enzyme by captopril offers a possible therapeutic approach to the treatment of atherosclerosis complicated with hypertension.
The role of the renin-angiotensin system in atherosclerosis is not clear. Campbell-Boswell & Robertson, Exp. and Mol. Pathol. 35:265 (1981) reported that angiotensin II stimulated proliferation of isolated human vascular smooth muscle cells while Geisterfer et al, Circ. Res. 62:749-756 (1988) showed no proliferation (but stimulation of growth) of isolated rat vascular smooth muscle cells.
Overturf, M. et al; Atherosclerosis, 59:383-399, 1986, discloses that studies with ACE inhibitors in cholesterol fed rabbits show no significant effects in the development of atherosclerosis.
Cecil, Textbook of Medicine, 16 Ed., pp 239 to 241, indicates at page 240 that blood pressure is an accelerator of atherosclerosis.
U.S. Pat. Nos. 4,046,889 and 4,105,776 to Ondetti et al disclose proline derivatives, including captopril, which are angiotensin converting enzyme (ACE) inhibitors useful for treating hypertension.
U.S. Pat. No. 4,337,201 to Petrillo discloses phosphinylalkanoyl substituted prolines, including fosinopril, which are ACE inhibitors useful for treating hypertension.
U.S. Pat. No. 4,374,829 discloses carboxyalkyl dipeptide derivatives, including enalapril, which are ACE inhibitors useful for treating hypertension.
U.S. Pat. No. 4,452,790 to Karanewsky et al discloses phosphonate substituted amino or imino acids and salts thereof and covers (S)-1-[6-amino-2-[[hydroxy(4-phenylbutyl)phosphinyl]-oxy]-1-oxohexyl]-L-pr oline (SQ 29,852, ceranapril). These compounds are ACE inhibitors useful in treating hypertension.
U.S. Pat. No. 4,316,906 to Ondetti et al discloses ether and thioether mercaptoacyl prolines which are ACE inhibitors useful in treating hypertension. This Ondetti et al patent covers zofenopril.
There are several different classes of compounds which have serum cholesterol lowering properties. Some of these compounds are inhibitors of the enzyme HMG CoA reductase which is essential in the production of cholesterol, such as mevastatin (disclosed in U.S. Pat. No. 3,983,140), lovastatin also referred to as mevinolin (disclosed in U.S. Pat. No. 4,231,938), pravastatin (disclosed in U.S. Pat. No. 4,346,227) and velostatin also referred to as synvinolin (disclosed in U.S. Pat. Nos. 4,448,784 and 4,450,171).
Other compounds which lower serum cholesterol may do so by an entirely different mechanism than the HMG CoA reductase inhibitors. For example, serum cholesterol may be lowered through the use of bile acid sequestrants such as cholestyramine, colestipol, DEAE-Sephadex and poly(diallylmethylamine) derivatives (such as disclosed in U.S. Pat. Nos. 4,759,923 and 4,027,009) or through the use of antihyperlipoproteinemics such as probucol and gemfibrozil which apparently lower serum "low density lipoproteins" (LDL) and/or converts LDL into high density lipoproteins (HDL).
U.S. Pat. No. 4,759,923 mentioned above discloses that poly(diallylmethylamine) derivatives which are bile salt sequestrants may be used in conjunction with drugs which reduce serum cholesterol by mechanisms other than sequestration, such as clofibrate, nicotinic acid, probucol, neomycin, p-aminosalicylic acid or mevinolin (also referred to as lovastatin).
Squalene synthetase is a microsomal enzyme which catalyzes the reductive dimerization of two molecules of farnesyl pyrophosphate (FPP) in the presence of nicotinamide adenine dinucleotide phosphate (reduced form) (NADPH) to form squalene (Poulter, C. D.; Rilling, H. C., in "Biosynthesis of Isoprenoid Compounds", Vol. I, Chapter 8, pp. 413-441, J. Wiley and Sons, 1981 and references therein). This enzyme is the first committed step of the de novo cholesterol biosynthetic pathway. The selective inhibition of this step should allow the essential pathways to isopentenyl tRNA, ubiquinone, and dolichol to proceed unimpeded. Squalene synthetase, along with HMG-CoA reductase has been shown to be down-regulated by receptor mediated LDL uptake (Faust, J. R.; Goldstein, J. L.; Brown, M. S. Proc. Nat. Acad. Sci. USA, 1979, 76, 5018-5022), lending credence to the proposal that inhibiting squalene synthetase will lead to an up-regulation of LDL receptor levels, as has been demonstrated for HMG-CoA reductase, and thus ultimately should be useful for the treatment and prevention of hypercholesterolemia and atherosclerosis.
One approach to inhibitors of squalene synthetase is to design analogs of the substrate FPP. It is clear from the literature that the pyrophosphate moiety is essential for binding to the enzyme. However, such pyrophosphates are unsuitable as components of pharmacological agents due to their chemical and enzymatic lability towards allylic C-O cleavage, as well as their susceptibility to metabolism by phosphatases.
P. Ortiz de Montellano et al in J. Med. Chem., 1977, 20, 243-249 describe the preparation of a series of substituted terpenoid pyrophosphates (Table A), and have shown these to be competitive inhibitors of the squalene synthetase enzyme. These substances retain the unstable allylic pyrophosphate moiety of FPP.
TABLE A ______________________________________ ##STR1## No. X Y Z ______________________________________ 1 CH.sub.3 CH.sub.3 H 2 H H H 3 C.sub.2 H.sub.5 H H 4 I H H 5 H I H 6 CH.sub.3 H SCH.sub.3 ______________________________________
Corey and Volante, J. Am. Chem. Soc. 1976, 98, 1291-3, have prepared FPP analog A and presqualene pyrophosphate (PSQ-PP) analog B as inhibitors of squalene biosynthesis. (Presqualene pyrophosphate is an intermediate in the conversion of FPP to squalene). These inhibitors possess methylene groups in place of the allylic oxygen moiety of FPP and PSQ-PP, but still retain the chemically and enzymatically unstable pyrophosphate linkage. ##STR2##
Poulter and co-workers have prepared cyclopropane C (Sandifer, R. M., et al., J. Am. Chem. Soc. 1982, 104, 7376-8) which in the presence of inorganic pyrophosphate is an intermediate analog inhibitor of the enzyme squalene synthetase. ##STR3##
Altman and co-workers, Bertolino, A., et al., Biochim. Biophys. Acta. 1978, 530, 17-23, reported that farnesyl amine and related derivatives D inhibit squalene synthetase, but provide evidence that this inhibition is non-specific and probably related to membrane disruption. ##STR4##
Poulter, C. D., et al, J. Org. Chem., 1986, 51, 4768, prepared compound E in a demonstration of a synthetic method, but did not report any biological data. ##STR5##
Poulter, C. D., Stremler, K. E., J.A.C.S., 1987, 109, 5542 describes the synthesis and biological evaluation of compounds having structure F. These compounds were evaluated as alternative substrates for avian liver farnesyl diphosphate and lemon peel cyclase. ##STR6##
McClard, R. W. and Poulter, C. D., et al., J.A.C.S. 1987, 109, 5544, reported that phosphinylphosphonates G and H were competitive inhibitors of the 1'-4-condensation between isopentenyl diphosphate and geranyl diphosphate catalyzed by avian liver farnesyl diphosphate synthetase. Phosphinylphosphonates G and H had Ki's of 19 .mu.M and 71 .mu.M, respectively. They also reported the speculative isolation of the farnesyl phosphinylphosphonate I, and the geranyl phosphinylphosphonate J from the enzymatic reaction of G with geranyl pyrophosphate or dimethylallyl pyrophosphate, respectively. The structures of I and J were tentatively assigned based on relative TLC mobilities. They hypothesized that I could be a potential inhibitor of squalene synthetase. ##STR7##
Capson, T. L., PhD dissertation, June 1987, Dept. of Medicinal Chemistry, the University of Utah, Abstract, Table of Contents, pp. 16, 17, 40-43, 48-51, Summary, discloses cyclopropanes of the structure discloses cyclopropanes of the structure ##STR8## as intermediate analog inhibitors of squalene synthetase.
S. A. Biller et al., Journal of Medicinal Chemistry, 1988, Vol. 31, No. 10, pp 1869 to 1871 disclose that isoprenoid (phosphinylmethyl) phosphonates (PMPs) inhibit squalene synthetase. These phosphonates have the structures
______________________________________ ##STR9## ##STR10## R.sup.1 ______________________________________ ##STR11## b ##STR12## c ##STR13## d ##STR14## ______________________________________
U.S. Pat. Nos. 4,871,721 and 4,924,024 disclose phosphorus-containing squalene synthetase inhibitors of the structure ##STR15##